Millo is a young Chinese-African-Cuban girl living in Havana during the late 1920s and early 1930s. She harbors a deep passion for playing the conga, bongó, and timbales drums. Because her society believes only boys should play drums, she initially keeps her musical aspirations a secret. She practices quietly on furniture and listens closely to the rhythmic sounds of nature and city life to fulfill her need for music.

Matias is Millo's father, who works as a greengrocer to support his large family of thirteen children in Havana. He represents the traditional societal views of his time, insisting that girls should not play drums. He acts as a gatekeeper to Millo's artistic goals before eventually seeking out a professional evaluation for his daughter's persistent interest.

The music teacher is a male professional who steps into Millo's life to objectively judge her drumming skills. As an established musician within a patriarchal system, he possesses the authority to determine if her talent merits public recognition. He works closely with Millo to expand her knowledge and prepares her for her first open-air café performance.

Cuchito is Millo's oldest sister. Recognizing the musical talent within her family, she takes the initiative to start Anacaona, an all-girl dance group. She is impressed by Millo's drumming abilities and wants her younger sister to join the ensemble, showing early support for female musicianship.